That’s actually more common than you think. It’s not explicit.

My niece who works at a very popular coffee shop where some are unioned, the non-union ones get paid a bit extra and reminded on the daily about that benefit of higher pay for being non-unioned.

And my aunt works as a receptionist in a non-union hospital. Her counterparts in a union, when they went on strike and got a huge pay bump… She suddenly “mysteriously” got a pay bump aligned with it because the non-union hospital was afraid of employees unionizing (which secretly, they were).